Kieran Culkin Confesses to Swapping Mark Ruffalo’s Prop Joint with Real Weed: ‘I Was 17 and Stupid’

Turns out Kieran Culkin is more of “A Real Pain” than his recent Golden Globe-nominated performance suggests. In a recent interview with The Guardian, the “Succession” actor revealed that almost 25 years ago, while performing in a production of James Lapine’s “The Moment When,” it was he who switched Mark Ruffalo‘s prop joint for one filled with real marijuana, forcing Ruffalo to perform high during opening night of the show. Ruffalo had previously recounted this experience in 2012 on The Graham Norton Show while promoting the first “Avengers” film.

“There was a play that I did that I smoked a joint in the first scene,” said Ruffalo, “and of course there was a very naughty young actor I was in the play with who on the opening night, with all the critics, he slipped a real joint onto the prop table.”

Consummate professional that he is, Ruffalo did not reveal the name of the young actor, but now he’ll never have to, as Culkin himself has come forward to accept responsibility for the prank.

“I was 17 and stupid,” he said, fessing up. He added later of apologizing to Ruffalo in the moment, “I’m like, ‘I thought this was a good prank. I’m stupid. Oh my God, I’m so sorry.’ But actually, they loved it. Mark says, ‘I haven’t smoked pot in 10 years; the second half’s going to be so much fun.’ There was this other actor who had never smoked pot in her life. She goes, ‘Is this what being high is? This is lovely.’ And then Phyllis Newman comes in and goes, ‘I haven’t smoked pot since the 1960s. Thank you, darling.’”

Unfortunately, not everyone involved in the production was as enthused by Culkin’s gesture.

“The stage manager comes stomping in and goes, ‘I don’t care whose it is, or what happened, but Kieran, give me the joint,'” said Culkin. “I sheepishly handed her the roach and she said, ‘Ruin your life on your own time.’”

For anyone concerned or hopeful Culkin might pull a similar stunt during his return to Broadway this spring in David Mamet’s “Glengarry Glen Ross,” co-starring Bob Odenkirk, Bill Burr, and Michael McKean, the play does not in fact feature anyone smoking weed at any point. However, even if it did, Culkin told The Guardian he’s very much past such childish shenanigans.

“I’m 42 now,” he said. “I know better. I’m not going to try to get anyone high on stage.”

To hear Ruffalo’s recollection of the experience, watch the clip from his 2012 episode of The Graham Norton Show below.